WLD/Hazards/TBT-WLD-009

Welding on Coated or Painted Steel

Welding & Fabrication › Hazards › Welding on Coated or Painted Steel

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Welding on coated or painted steel generates additional toxic fumes from the coating decomposition.
Zinc coatings on galvanised steel produce zinc oxide fume that causes metal fume fever within hours.
Lead-based paints on older steelwork produce toxic lead fume during welding and cutting operations.
Chromate primers and anti-corrosion coatings release hexavalent chromium fume, a confirmed carcinogen.
Cadmium-plated components produce extremely toxic cadmium fume that can be fatal in enclosed spaces.
Organic coatings including epoxy, polyurethane, and bitumen generate irritant and potentially carcinogenic fumes.
COSHH 2002 requires a specific assessment for welding on each type of coating or paint encountered.
Removing coatings before welding by grinding or blasting is the preferred control but generates dust.
Local exhaust ventilation must capture coating fumes at source before they enter the breathing zone.
RPE rated for metal fume and organic vapour may be required in addition to LEV for coated steel.

Metal fume fever	Zinc fume from galvanised steel causes flu-like metal fume fever within hours, with repeated exposure increasing severity.
Cancer risk	Chromate primers and cadmium coatings produce carcinogenic fumes. Even short exposures create long-term cancer risk.
Lead poisoning	Welding on old lead-painted steel causes lead fume inhalation, accumulating in the body and damaging the nervous system.

Don't

Identify the coating type from the safety data sheet before welding begins.
Complete a specific COSHH assessment for welding on the identified coating.
Remove coatings from the weld zone by grinding before welding where practicable.
Use LEV positioned close to the arc to capture coating fumes at source.
Wear RPE rated for metal fume and organic vapour as the COSHH assessment requires.
Monitor for lead exposure if welding on steelwork with suspected lead paint.
Ventilate the work area thoroughly when welding on galvanised or coated steel.
Attend health surveillance including blood lead testing when working on lead paint.
Wash hands and face before eating or drinking after welding on coated steel.
Brief the welder on the specific coating hazards and required controls each time.

DON'T weld on coated steel without identifying the coating type first.
DON'T assume galvanised steel fume is harmless; zinc oxide causes metal fume fever.
DON'T weld on lead-painted steel without lead fume controls and monitoring.
DON'T weld on cadmium-plated components in enclosed spaces; the fume is lethal.
DON'T skip the COSHH assessment for each different coating type encountered.
DON'T weld without LEV even if the coating has been partially removed.
DON'T eat or drink after handling or welding coated steel without washing first.
DON'T ignore flu-like symptoms after welding galvanised steel; report them.
DON'T burn off coatings with a torch as a removal method; it creates more fume.
DON'T assume modern coatings are safe; many contain hazardous chemical components.

See also: Welding Fume Extraction and LEV | Welding Safety Awareness (Comprehensive)

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